Impact of the Korea Early Childhood Home-visiting Intervention on Childhood Health and Development and Maternal Health: A Randomized Controlled Community Trial
Trial Snapshot
- Phase
- Not Applicable
- Status
- Active, not recruiting
- Enrollment
- 800
- Locations
- 2
- Primary Endpoint
- School readiness (EDI)
Study Overview
Brief Summary
Maternal and early childhood home visits have been proposed as an effective strategy to improve the health and development of disadvantaged children. In South Korea (hereafter, Korea), a maternal and early childhood home visit program has been implemented since 2013 in Seoul, and then was adopted in 2019 by the central government as a national policy for child health and development.
The Korea Early Childhood Home-visiting Intervention (KECHI) encompasses 25-29 home visits, group activities, and community service linkage by social workers from the prenatal period until the child reaches the age of 2 years; as such, it is a complex intervention involving various domains to address a wide range of outcomes. Each home visit is implemented based on the family's needs, and individualized interventions are provided to improve parenting and the home environment in order to promote children's health and development and maternal health.
This study is a randomized controlled community trial conducted in Korea to examine the impact of targeted home visits led by nurses in the prenatal and early childhood period on children's health and development and maternal health.
This study is a superiority trial with two parallel groups from pregnancy until the child reaches 2 years of age. Pregnant women with two or more risk factors will be recruited to participate in the study after they provide informed consent. Participants will then be randomly assigned to the intervention or control group with a 1:1 allocation through an independent web-based random allocation system. We expect a total of 800 families (400 families in each group) to be recruited. The intervention group will receive the KECHI program and the control group will receive existing maternal and child health services (usual care), but not multiple home visits by nurses. Both groups will receive gift cards of 30,000 Korean won (about 27 USD) for each round of surveys.
The intervention and control groups will be surveyed on the outcome variables of home environment, child development, breastfeeding, maternal health, child hospital visits due to injuries, and community service linkage at four home visits by trained research nurses at baseline and at 6 months, 12 months, and 24 months after birth. Telephone contact will also be made at 6 weeks and 18 months after birth for both groups. Outcome measurements will be performed by research nurses and data management will be conducted by statistical analysts. The analysis will be conducted for the intention-to-treat (ITT) and per-protocol (PP) groups, with an interim analysis of outcomes up to the 6-month follow-up. For the primary outcomes and certain secondary outcomes, subgroup analyses will be performed based on factors such as region, fertility status, number of risk factors, presence of depression, education level, etc. Furthermore, this study will utilize administrative data available for all study participants to evaluate both short and long-term impacts of the KECHI intervention on maternal and child outcomes.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Prevention
- Masking
- None
Masking Description
The research management staff, home visit nurses (intervention teams), and study participants will be aware of the allocation results. However, the research nurses making outcome assessments will be blinded to the randomization, and families will be asked not to disclose their group status during the surveys. The research nurses (outcome assessors) will only be notified of the survey schedules (6 weeks, 6 months, 12 months, and 24 months) of both groups so that the outcome indicators can be measured with blinding maintained. Statistical analysts will not be able to access the randomization variable until all 2 years of data are collected.
Eligibility Criteria
- Sex
- Female
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •Pregnant women with two or more risk factors at the time of screening
- •Pregnant women at less than 37 weeks of gestation
- •Pregnant women who can read and answer questionnaires in Korean
Exclusion Criteria
- •Pregnant women who have experienced any critical event such as termination of pregnancy, stillbirth, or child death
- •Pregnant women who plan to move abroad or to other regions where the KECHI service is not available within the next 6 months
Arms & Interventions
Targeted nurse-led home visiting
The intervention group will receive 25-29 home visits during pregnancy and the first 2 years of life conducted by child health nurses. The frequency of home visits will be determined by nurses based on the needs of the families. The content of each home visit is individually tailored to the mother's needs, skills, strengths, and capacity using parenting education materials.
Intervention: Targeted nurse-led home visiting (Behavioral)
Control group
The control group will receive existing maternal and child health services (usual care) except for the targeted nurse-led home visits.
Outcomes
Primary Outcomes
School readiness (EDI)
Time Frame: when the child is 66 months old
School readiness as assessed using the Korean Early Development Instrument (EDI) administered by the child's teacher. The EDI evaluates children's overall developmental readiness for school across five domains: (1) Physical Health and Well-being, (2) Social Competence, (3) Emotional Maturity, (4) Language and Cognitive Development, and (5) Communication Skills and General Knowledge. The assessment consists of approximately 100 items based on teacher observations and takes 15-20 minutes per child to complete.
Maternal parenting behavior (32-PSDQ)
Time Frame: when the child is 66 months old
Maternal parenting behavior as assessed using the 32-item Parenting Style and Dimensions Questionnaire (32-PSDQ), measuring authoritative, authoritarian, and permissive parenting styles, adapted from Robinson et al. (2001) and used in the Korean Early Childhood Education and Care Panel Study.
Cognitive-stimulating home environment (Parent-child interaction)
Time Frame: when the child is 66 months old
Cognitive-stimulating home environment as assessed using the Home Environment Activities and Cognitive Stimulation (HEQ) questionnaire adapted from the Early Childhood Longitudinal Study Kindergarten Cohort (ECLS-K) when the child is 66 months old. The Korean version was translated by the Korea Institute of Child Care and Education. The instrument consists of 10 items measuring frequency of cognitive stimulation activities between parents and children over the past week, rated on a 4-point scale.
Home environment
Time Frame: when the child is 24 months old.
Home environment as assessed using IT-HOME (Infant-Toddler Home Observation for Measurement of Environment) when the child is 24 months old. IT-HOME (Infant-Toddler Home Observation for Measurement of Environment), composed of 45 items, was developed by Caldwell \& Bradley (1984). The minimum score is 0 and the maximum score is 45, and a higher score means a better outcome.
Emergency department visits due to injuries
Time Frame: when the child is 24 months old.
Number of emergency department visits due to injuries when the child is 24 months old.
Child development (K-Bayley-III)
Time Frame: when the child is 24 months old.
Child development as assessed using the K-Bayley-III (Korean Bayley Scales of Infant and Toddler Development-III) score when the child is 24 months old
Breastfeeding duration
Time Frame: when the child is 24 months old.
Breastfeeding duration when the child is 24 months old.
Maternal self-rated health
Time Frame: when the child is 24 months old.
Maternal self-rated health when the child is 24 months old.
Community service linkage
Time Frame: when the child is 24 months old.
Community service linkage as measured by the number of community services a mother has received during the last year when the child is 24 months old.
School readiness (EDI)
Time Frame: when the child is 66 months old
School readiness as assessed using the Korean Early Development Instrument (EDI) administered by the child's teacher. The EDI evaluates children's overall developmental readiness for school across five domains: (1) Physical Health and Well-being, (2) Social Competence, (3) Emotional Maturity, (4) Language and Cognitive Development, and (5) Communication Skills and General Knowledge. The assessment consists of approximately 100 items based on teacher observations and takes 15-20 minutes per child to complete.
Child Intelligence (WPPSI)
Time Frame: when the child is 66 months old
Child intelligence assessed using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-IV) administered by trained occupational therapist. The assessment measures overall intellectual ability and cognitive development.
Child abuse
Time Frame: when the child is 66 months old
Number of child abuse reports obtained through secondary data linkage with the Social Security Information Service's child abuse reporting database.
Emergency department visits due to injuries (administrative data)
Time Frame: when the child is 66 months old
Number of emergency department visits due to injuries (indirect indicator of child abuse) obtained via linkage with Korea National Health Insurance Service (NHIS) claims data.
Maternal depression (PHQ-9)
Time Frame: when the child is 66 months old
Maternal depression as assessed using the PHQ-9 (Patient Health Questionnaire-9) when the child is 66 months old. The PHQ-9 (Patient Health Questionnaire-9) was developed by Kroenke, K. et al. (2001) as a tool measuring the depression level of adults and composed of 9 items. The minimum score is 0 and the maximum score is 27, and higher score means a worse outcome.
Maternal parenting behavior
Time Frame: when the child is 54 months old
Maternal parenting behavior as assessed using a 17-item questionnaire measuring two dimensions: warm/responsive parenting and controlling parenting when the child is 54 months old. The warm/responsive dimension includes 9 items adapted by the Korea Institute of Child Care and Education from the Parental Style Questionnaire (Bornstein et al., 1996). The controlling dimension includes 8 items adapted by the Korea Institute of Child Care and Education based on Cho et al. (1999). Responses are rated on a 5-point Likert scale, with higher scores indicating greater endorsement of each parenting style.
Maternal parenting behavior (32-PSDQ)
Time Frame: when the child is 66 months old
Maternal parenting behavior as assessed using the 32-item Parenting Style and Dimensions Questionnaire (32-PSDQ), measuring authoritative, authoritarian, and permissive parenting styles, adapted from Robinson et al. (2001) and used in the Korean Early Childhood Education and Care Panel Study.
Cognitive-stimulating home environment (Parent-child interaction)
Time Frame: when the child is 66 months old
Cognitive-stimulating home environment as assessed using the Home Environment Activities and Cognitive Stimulation (HEQ) questionnaire adapted from the Early Childhood Longitudinal Study Kindergarten Cohort (ECLS-K) when the child is 66 months old. The Korean version was translated by the Korea Institute of Child Care and Education. The instrument consists of 10 items measuring frequency of cognitive stimulation activities between parents and children over the past week, rated on a 4-point scale.
Home environment
Time Frame: when the child is 6 months old.
Home environment as assessed using IT-HOME (Infant-Toddler Home Observation for Measurement of Environment) when the child is 6 months old. IT-HOME (Infant-Toddler Home Observation for Measurement of Environment), composed of 45 items, was developed by Caldwell \& Bradley (1984). The minimum score is 0 and the maximum score is 45, and a higher score means a better outcome.
Home environment
Time Frame: when the child is 12 months old.
Home environment as assessed using IT-HOME (Infant-Toddler Home Observation for Measurement of Environment) when the child is 12 months old. IT-HOME (Infant-Toddler Home Observation for Measurement of Environment), composed of 45 items, was developed by Caldwell \& Bradley (1984). The minimum score is 0 and the maximum score is 45, and a higher score means a better outcome.
Emergency department visits due to injuries
Time Frame: when the child is 6 weeks old.
Number of emergency department visits due to injuries when the child is 6 weeks old.
Emergency department visits due to injuries
Time Frame: when the child is 6 months old.
Number of emergency department visits due to injuries when the child is 6 months old.
Emergency department visits due to injuries
Time Frame: when the child is 12 months old.
Number of emergency department visits due to injuries when the child is 12 months old.
Breastfeeding duration
Time Frame: when the child is 6 weeks old.
Breastfeeding duration when the child is 6 weeks old.
Breastfeeding duration
Time Frame: when the child is 6 months old.
Breastfeeding duration when the child is 6 months old.
Breastfeeding duration
Time Frame: when the child is 12 months old.
Maternal self-rated health when the child is 12 months old.
Maternal self-rated health
Time Frame: when the child is 6 weeks old.
Maternal self-rated health when the child is 6 weeks old.
Maternal self-rated health
Time Frame: when the child is 6 months old.
Maternal self-rated health when the child is 6 months old.
Maternal self-rated health
Time Frame: when the child is 12 months old.
Maternal self-rated health when the child is 12 months old.
Maternal self-rated health
Time Frame: when the child is 18 months old.
Maternal self-rated health when the child is 18 months old.
Community service linkage
Time Frame: when the child is 12 months old.
Community service linkage as measured by the number of community services a mother has received during the last year when the child is 12 months old.
Maternal depression (PHQ-9)
Time Frame: when the child is 42 months old
Maternal depression as assessed using the PHQ-9 (Patient Health Questionnaire-9) when the child is 42 months old. The PHQ-9 (Patient Health Questionnaire-9) was developed by Kroenke, K. et al. (2001) as a tool measuring the depression level of adults and composed of 9 items. The minimum score is 0 and the maximum score is 27, and higher score means a worse outcome.
Maternal depression (PHQ-9)
Time Frame: when the child is 54 months old
Maternal depression as assessed using the PHQ-9 (Patient Health Questionnaire-9) when the child is 54 months old. The PHQ-9 (Patient Health Questionnaire-9) was developed by Kroenke, K. et al. (2001) as a tool measuring the depression level of adults and composed of 9 items. The minimum score is 0 and the maximum score is 27, and higher score means a worse outcome.
Maternal parenting behavior
Time Frame: when the child is 42 months old
Maternal parenting behavior as assessed using a 17-item questionnaire measuring two dimensions: warm/responsive parenting and controlling parenting when the child is 42 months old. The warm/responsive dimension includes 9 items adapted by the Korea Institute of Child Care and Education from the Parental Style Questionnaire (Bornstein et al., 1996). The controlling dimension includes 8 items adapted by the Korea Institute of Child Care and Education based on Cho et al. (1999). Responses are rated on a 5-point Likert scale, with higher scores indicating greater endorsement of each parenting style.
Cognitive-stimulating home environment (Parent-child interaction)
Time Frame: when the child is 42 months old
Cognitive-stimulating home environment as assessed using the Home Environment Activities and Cognitive Stimulation (HEQ) questionnaire adapted from the Early Childhood Longitudinal Study Kindergarten Cohort (ECLS-K) when the child is 42 months old. The Korean version was translated by the Korea Institute of Child Care and Education. The instrument consists of 10 items measuring frequency of cognitive stimulation activities between parents and children over the past week, rated on a 4-point scale.
Cognitive-stimulating home environment (Parent-child interaction)
Time Frame: when the child is 54 months old
Cognitive-stimulating home environment as assessed using the Home Environment Activities and Cognitive Stimulation (HEQ) questionnaire adapted from the Early Childhood Longitudinal Study Kindergarten Cohort (ECLS-K) when the child is 54 months old. The Korean version was translated by the Korea Institute of Child Care and Education. The instrument consists of 10 items measuring frequency of cognitive stimulation activities between parents and children over the past week, rated on a 4-point scale.
Secondary Outcomes
- Maternal alcohol consumption(when the child is 66 months old.)
- Delivery type(when the child is 6 weeks old.)
- Spousal intimacy(when the child is 24 months old.)
- Spousal tobacco use(when the child is 24 months old.)
- Spousal alcohol consumption(when the child is 24 months old.)
- Safety knowledge(when the child is 24 months old.)
- Spousal participation in parenting(when the child is 24 months old.)
- Parenting related household expenses(when the child is 24 months old.)
- Anxiety(when the child is 24 months old.)
- Maternal tobacco use(when the child is 24 months old.)
- Maternal alcohol consumption(when the child is 24 months old.)
- Maternal parenting stress(when the child is 24 months old.)
- Intimate partner violence(when the child is 24 months old.)
- Social support(when the child is 24 months old.)
- Food insecurity(when the child is 24 months old.)
- Safety knowledge(when the child is 66 months old)
- Emergency department visits(when the child is 24 months old.)
- Hospital admission(when the child is 24 months old.)
- Child development (Denver II)(when the child is 24 months old.)
- Premature birth(when the child is 6 weeks old.)
- Delayed growth - height(when the child is 24 months old.)
- Delayed growth - weight(when the child is 24 months old.)
- Delayed growth - head circumference(when the child is 24 months old.)
- Knowledge of SIDS (sudden infant death syndrome) prevention(when the child is 6 months old.)
- Vaccination(when the child is 24 months old.)
- Spousal participation in parenting(when the child is 66 months old.)
- Parenting related household expenses(when the child is 66 months old.)
- Intention to have another child(when the child is 24 months old.)
- Experience of delivery in the past 2 years(when the child is 24 months old.)
- Depression (EPDS)(when the child is 24 months old.)
- Suicidal ideation(when the child is 24 months old.)
- Depression (PHQ-9)(when the child is 24 months old.)
- Depression (Whooley & Arroll questions)(when the child is 18 months old.)
- Anxiety(when the child is 66 months old.)
- Maternal tobacco use(when the child is 66 months old.)
- Maternal parenting stress(when the child is 66 months old.)
- Intimate partner violence(when the child is 66 months old.)
- Maternal body weight(when the child is 24 months old.)
- Social support(when the child is 66 months old.)
- Food insecurity(when the child is 66 months old.)
- Spousal intimacy(when the child is 66 months old.)
- Spousal tobacco use(when the child is 66 months old.)
- Spousal alcohol consumption(when the child is 66 months old.)
- Parent-child interaction(when the child is 24 months old.)
- Emergency department visits due to injuries (maternal-report)(when the child is 66 months old.)
- Hospital admission (maternal-report)(when the child is 66 months old.)
- Subsequent childbirth after study participation(when the child is 66 months old.)
- Maternal employment status(when the child is 66 months old.)
- Paternal employment status (maternal-report)(when the child is 66 months old)
- Monthly household income(when the child is 66 months old)
- Basic livelihood security status(when the child is 66 months old.)
- Maternal marital status(when the child is 66 months old.)
- Child's Educational facility attendance(when the child is 66 months old.)
- Parental efficacy(when the child is 66 months old.)
- Self-efficacy(when the child is 66 months old.)
- Healthcare utilization (administrative data)(when the child is 66 months old.)
- National health check-ups (administrative data)(when the child is 66 months old.)
- Child lifestyle habits(when the child is 66 months old.)
- Child problem behavior(when the child is 66 months old.)
- Child social-emotional development (social competence)(when the child is 66 months old.)
- Child BMI(when the child is 66 months old.)
- Child dental caries(when the child is 66 months old.)
- Child health status(when the child is 66 months old.)
- Maternal self-rated health(when the child is 66 months old.)
- Vaccination (administrative data)(when the child is 66 months old.)
- Community service linkage(when the child is 66 months old.)
- Maternal quality of life(when the child is 66 months old.)
- National health check-ups(when the child is 24 months old.)
- Maternal self-rated health(when the child is 66 months old.)
- Safety knowledge(when the child is 66 months old)
- Emergency department visits(when the child is 24 months old.)
- Hospital admission(when the child is 24 months old.)
- Child development (Denver II)(when the child is 24 months old.)
- Premature birth(when the child is 6 weeks old.)
- Delayed growth - height(when the child is 24 months old.)
- Delayed growth - weight(when the child is 24 months old.)
- Delayed growth - head circumference(when the child is 24 months old.)
- Knowledge of SIDS (sudden infant death syndrome) prevention(when the child is 6 months old.)
- Vaccination(when the child is 24 months old.)
- National health check-ups(when the child is 24 months old.)
- Spousal participation in parenting(when the child is 66 months old.)
- Depression (EPDS)(when the child is 24 months old.)
- Parenting related household expenses(when the child is 66 months old.)
- Intention to have another child(when the child is 24 months old.)
- Experience of delivery in the past 2 years(when the child is 24 months old.)
- Suicidal ideation(when the child is 24 months old.)
- Depression (PHQ-9)(when the child is 24 months old.)
- Depression (Whooley & Arroll questions)(when the child is 18 months old.)
- Anxiety(when the child is 66 months old.)
- Maternal tobacco use(when the child is 66 months old.)
- Maternal alcohol consumption(when the child is 66 months old.)
- Delivery type(when the child is 6 weeks old.)
- Child BMI(when the child is 66 months old.)
- Maternal parenting stress(when the child is 66 months old.)
- Intimate partner violence(when the child is 66 months old.)
- Maternal body weight(when the child is 24 months old.)
- Social support(when the child is 66 months old.)
- Food insecurity(when the child is 66 months old.)
- Spousal intimacy(when the child is 66 months old.)
- Spousal tobacco use(when the child is 66 months old.)
- Spousal alcohol consumption(when the child is 66 months old.)
- Parent-child interaction(when the child is 24 months old.)
- Emergency department visits due to injuries (maternal-report)(when the child is 66 months old.)
- Hospital admission (maternal-report)(when the child is 66 months old.)
- Child dental caries(when the child is 66 months old.)
- Child health status(when the child is 66 months old.)
- Subsequent childbirth after study participation(when the child is 66 months old.)
- Maternal employment status(when the child is 66 months old.)
- Paternal employment status (maternal-report)(when the child is 66 months old)
- Monthly household income(when the child is 66 months old)
- Basic livelihood security status(when the child is 66 months old.)
- Maternal marital status(when the child is 66 months old.)
- Child's Educational facility attendance(when the child is 66 months old.)
- Parental efficacy(when the child is 66 months old.)
- Self-efficacy(when the child is 66 months old.)
- Healthcare utilization (administrative data)(when the child is 66 months old.)
- National health check-ups (administrative data)(when the child is 66 months old.)
- Child lifestyle habits(when the child is 66 months old.)
- Child problem behavior(when the child is 66 months old.)
- Child social-emotional development (social competence)(when the child is 66 months old.)
- Vaccination (administrative data)(when the child is 66 months old.)
- Community service linkage(when the child is 66 months old.)
- Maternal quality of life(when the child is 66 months old.)
- Child's Educational facility attendance(when the child is 42 months old.)
- Child's Educational facility attendance(when the child is 54 months old.)
- Parental efficacy(when the child is 42 months old.)
- Emergency department visits(when the child is 6 weeks old.)
- Safety knowledge(when the child is 6 months old.)
- Safety knowledge(when the child is 12 months old.)
- Emergency department visits(when the child is 6 months old.)
- Emergency department visits(when the child is 12 months old.)
- Hospital admission(when the child is 6 weeks old.)
- Hospital admission(when the child is 6 months old.)
- Hospital admission(when the child is 12 months old.)
- Child development (Denver II)(when the child is 6 months old.)
- Child development (Denver II)(when the child is 12 months old.)
- Delayed growth - height(when the child is 6 months old.)
- Delayed growth - height(when the child is 12 months old.)
- Delayed growth - weight(when the child is 6 months old.)
- Delayed growth - weight(when the child is 12 months old.)
- Delayed growth - head circumference(when the child is 6 months old.)
- Delayed growth - head circumference(when the child is 12 months old.)
- Vaccination(when the child is 6 months old.)
- Vaccination(when the child is 12 months old.)
- National health check-ups(when the child is 6 months old.)
- National health check-ups(when the child is 12 months old.)
- Spousal participation in parenting(when the child is 6 months old.)
- Spousal participation in parenting(when the child is 12 months old.)
- Parenting related household expenses(when the child is 6 months old.)
- Parenting related household expenses(when the child is 12 months old.)
- Depression (EPDS)(when the child is 6 months old.)
- Depression (EPDS)(when the child is 12 months old.)
- Suicidal ideation(when the child is 6 months old.)
- Suicidal ideation(when the child is 12 months old.)
- Maternal body weight(when the child is 6 months old.)
- Depression (PHQ-9)(when the child is 6 months old.)
- Depression (PHQ-9)(when the child is 12 months old.)
- Depression (Whooley & Arroll questions)(when the child is 6 weeks old.)
- Anxiety(when the child is 6 months old.)
- Maternal body weight(when the child is 12 months old.)
- Anxiety(when the child is 12 months old.)
- Maternal tobacco use(when the child is 6 months old.)
- Maternal tobacco use(when the child is 12 months old.)
- Maternal alcohol consumption(when the child is 6 months old.)
- Maternal alcohol consumption(when the child is 12 months old.)
- Maternal parenting stress(when the child is 6 months old.)
- Maternal parenting stress(when the child is 12 months old.)
- Intimate partner violence(when the child is 6 months old.)
- Intimate partner violence(when the child is 12 months old.)
- Maternal body weight(when the child is 6 weeks old.)
- Social support(when the child is 6 months old.)
- Social support(when the child is 12 months old.)
- Food insecurity(when the child is 12 months old.)
- Spousal intimacy(when the child is 6 months old.)
- Spousal intimacy(when the child is 12 months old.)
- Spousal tobacco use(when the child is 6 months old.)
- Spousal tobacco use(when the child is 12 months old.)
- Spousal alcohol consumption(when the child is 6 months old.)
- Spousal alcohol consumption(when the child is 12 months old.)
- Parent-child interaction(when the child is 12 months old.)
- Safety knowledge(when the child is 42 months old)
- Safety knowledge(when the child is 54 months old)
- Emergency department visits due to injuries (maternal-report)(when the child is 42 months old.)
- Emergency department visits due to injuries (maternal-report)(when the child is 54 months old.)
- Anxiety(when the child is 42 months old.)
- Anxiety(when the child is 54 months old.)
- Maternal employment status(when the child is 42 months old.)
- Maternal employment status(when the child is 54 months old.)
- Maternal marital status(when the child is 42 months old.)
- Maternal marital status(when the child is 54 months old.)
- Parental efficacy(when the child is 54 months old.)
- Child health status(when the child is 42 months old.)
- Child health status(when the child is 54 months old.)
- Maternal self-rated health(when the child is 42 months old.)
- Maternal self-rated health(when the child is 54 months old.)
Investigators
Young-Ho Khang
Professor
Seoul National University Hospital